Patients with Multiple Sclerosis will be studied as a prototype model of an immune-mediated neurological disorder. Immune complexes in serum and spinal fluid will be measured using a solid phase Clq and Raji cell assay. Complexes from selected samples will be isolated, dissociated, and the component antigens and antibodies examined using ELISA, gel electrophoresis and immunoperoxidase techniques. Attempts will be made to identify a consistent immune complex component in the hopes of identifying an auto-antigen or infectious agent in this disease. Lymphocyte subpopulations in spinal fluid will be examined using monoclonal antibodies. The immune function of spinal fluid cells will be compared to peripheral cells with regard to lymphocyte transformation, antibody production, and the modulation of these responses by interferon and pertinent CNS antigens. The long term objectives of this proposal, besides the obvious one of learning more about the pathogenesis of Multiple Sclerosis, include the development of model approaches to 1. analyzing immune complexes in human diseases and 2. analyzing immune function of compartmentalized spinal fluid cells vs. peripheral cells in nervous system disorders.